This invention relates to a disposable diaper for absorbing and containing excretion.
Japanese Patent Application Publication No. 1997-191908A describes an open-type disposable diaper basically comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets and further comprising a pair of tape fasteners extending outward from transversely opposite side edge portions of a rear waist region in transverse direction and a target tape strip attached to outer surface of the backsheet in a front waist region. In this diaper of well known art, a loop member is used as the target tape strip and the respective tape fasteners are provided on their surfaces facing the target tape strip with hook members. The target tape strip serves as an anchoring zone for the tape fasteners. In this diaper of well known art, the hook members are engaged with the target tape strip and thereby the tape fasteners are fixed to the target tape strip so as to connect the front and rear waist regions to each other. A waist-opening and a pair of leg-openings are defined as the front and rear waist regions are connected together in this manner.
In the case of the diaper disclosed in the Publication, the transversely opposite side edge portions of the front and rear waist regions are moved as the legs of a wearer move and this movement is transmitted via the tape fasteners to the hook members. Depending on a degree of the diaper"" movement, a peeling force and/or a shearing force tending to disengage the hook members from the target tape strip are exerted upon the hook member and the target tape strip. Such peeling force and shearing force is generally concentrated in the vicinity of inner side edges of the respective hook members lying in the vicinity of the transversely opposite side edge portions of the rear waist region and in the vicinity of the target tape strip""s both side edges lying in the vicinity of the transversely opposite side edge portions of the front waist region.
In this diaper disclosed therein, the portions of the respective hook members defined in the vicinity of their inner side edges are bonded to the tape fasteners, so the portions of the hook member defined in the vicinity of their inner side edges are not freely movable under constraint by the tape fasteners. Consequently, the peeling force and shearing force are exerted directly upon the portions of the hook members defined in the vicinity of their inner side edges and the inner side edge portions of the hook members may be readily disengaged from the target tape strip.
Furthermore, the portions of the target tape strip defined in the vicinity of its both side edges are bonded to the backsheet, so these portions of the target tape strip are restrained by the diaper and not freely movable. As a result, if the portions of the hook members defined in the vicinity of their inner side edges come in engagement with the portions of the target tape strip defined in the vicinity of its both side edges, the peeling force and shearing force are exerted directly upon the portions of the hook members defined in the vicinity of their inner side edges as well as upon the portions of the target tape strip defined in the vicinity of its both side edges. With a consequence, the inner edge portions of the respective hook members may be easily disengaged from the target tape strip.
In the known diaper, disengagement between the hook members and the target tape strip rapidly proceeds as the inner side edges of the hook members are disengaged from the target tape strip until the hook members are completely disengaged from the target tape strip.
It is an object of this invention to provide a disposable diaper designed so that the hook members are not readily disengaged from the target tape strip even if the diaper moves after the front and rear waist regions have been connected to each other to put the diaper on a wearer""s body.
According to this invention, there is provided a disposable diaper with mechanical comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these top- and backsheets so as to define, in a longitudinal direction of the diaper, a front waist region, a rear waist region and a crotch region extending between these front and rear waist regions, a pair of tape fasteners being used to connect the front and rear waist regions to each other extend outward transversely opposite side edge portions of the rear waist region in a transverse direction and a target tape strip on which the tape fasteners are anchored being provided on an outer surface of the backsheet in the front waist region.
According to this invention one of a hook member and a loop member is provided on a surface of the tape fastener facing the target tape strip and a portion of the one member defined in vicinity of an inner edge of the one member and lying in vicinity of the associated side edge portion of the rear waist region is not bonded to the tape fastener but set free from the tape fastener; and the target tape strip is formed by the other of the hook member and the loop member.
According to one embodiment of this invention, portions of the target tape strip defined in vicinity of its both side edges and lying in vicinity of the transversely opposite side edge portions of the front waist region are not bonded to the backsheet but set free from the backsheet.
According to another embodiment of this invention, the target tape strip is bonded to the backsheet along a plurality of bonding zones spaced apart from one another by a predetermined dimension in the transverse direction and remaining zones defined between respective pairs of the adjacent bonding zones are not bonded to the backsheet but set free from the backsheet.